Geologic sequestration of CO2 is a promising control technology for greenhouse gases. However, applied on a wide scale, it will generate thousands of large CO2 deposits in the U.S., which could provoke environmental concern about CO2 “waste disposal” and jeopardize ambitious geologic sequestration R&D efforts. This concern could possibly be resolved by using methanogenic bacteria, which are known to naturally convert CO2 into CH4. As an additional benefit, new, readily exploitable natural gas deposits would be create in the process. This project will identify the most promising methanogen consortia and experimentally determine their growth capabilities and requirements under typical reservoir conditions. Phase I identified the six most promising methanogen consortia, the mechanisms by which they convert CO2 into CH4, and the general physico-chemical conditions needed to sustain this conversion. Oil and gas reservoirs in the U.S. were screened to define reservoir properties relevant to methanogen growth and identify potential sites for Phase II laboratory and field experiments. In Phase II, laboratory experiments will be conducted to incubate and optimize the growth of the selected methanogen species under varying physico-chemical conditions that reflect actual reservoir conditions at the St. Johns test site (a CO2 field in Arizona/New Mexico operated by an industry partner), as well as other potential CO2 test sites. Commercial Applications and Other Benefits as described by awardee: The successful application of naturally occurring methanogens to remediate CO2 sequestration sites would head off environmental objections to sequestration as waste disposal and open up this greenhouse-gas-reduction technology to widespread application by the power generation, chemical, petroleum, and other industries. The technology also could generate new natural gas resources and even could allow the conversion of sub-economic (high-CO2) natural gas deposits into pure and economical methane deposits
